Well apparatus for well formation testing



June 7, 1960 H. A. MORRISS, JR 2,939,532

WELL APPARATUS FOR WELL FORMATION TESTING Filed Jan. 26, 1955 2Sheets-Sheet l J? M Herberf A. Marr/avgz/r.

.i- I {a INVENTOR.

' 02" BY AM M;

A TTO/PA/E m June 7, 1960 H. A. MORRISS, JR

WELL APPARATUS FOR WELL FORMATION TESTING Filed Jan. 26, 1955 2 Sheets-Sheet 2 Her& erf A. Mar/us, z/r.

INVENTOR. BY WM A TTO/PA/[KS WELL APPARATUS FOR WELL FORMATION TESTINGHerbert A. Morriss, Jr., Shreveport, La., assignor to Georesearch, Inc,Shreveport, La., a corporation of Delaware Filed Jan. 26, 1955, Ser. No.484,187

6 Claims. (Cl. 166-63) This invention relates to new and usefulimprovements in apparatus for well formation testing.

It is an object of this invention to provide a new and improvedapparatus for effectively cleaning the wall of a well bore adjacent awell formation to facilitate the obtaining of a fluid sample from theWell formation.

An important object of this invention is to provide a new and improvedapparatus for obtaining a fluid sample from a. well formation in a wellbore wherein the wall of the well bore adjacent said well formation iscleaned substantially simultaneously with the taking of the fluidsample, such cleaning of the wall of the well bore being preferablycarried out by blasting the wall with an explosive charge.

Another object of this invention is to provide a. new

and improved apparatus for use in a well bore wherein the fluid pressurein the well bore is reduced upon the opening of a valve in aconventional formation tester device, such fluid pressure reductionelfecting a detonal tion of an explosive charge for cleaning the wall ofthe wellbore adjacent the well formation to be testedwhere by thecleaning of the wall of the well formation'and the taking of the samplewith the formation tester'issubstantially simultaneous which prevents amud cake'fronri forming on. the wall of the formation prior to theobtaining of the formation test sample.

"'A further object of this. invention is to provide a new.

and improved perforator apparatus for use in a well bore for perforatingthe wall of a well formation therein,

wherein the perforating apparatus is so constructed that' it isincapable offiring the explosive charge until the device is lowered intothe well bore and the fluid pressure.

in the well has been reduced below a predetermined amount. 4

Still another object-of this invention is to provide a new and improvedformation perforator apparatus wherein the fluid pressure of the well isinitially utilized to arm the firing mechanism upon insertion of theapparatus into a well bore.

The construction designed to carry out the invention will be hereinafterdescribed, together with other features thereof.

The invention will be more readily understood from" a reading of thefollowing specification and by reference to the accompanying drawingsforming a part thereof,.

'Figure 4 is an enlarged sectional view of the detonator 2, 9,532Patented- June 7, 1960- portion of the cleaner unit or deviceillustrated in Figure 2, with the actuator section in an unarmed orreleased position.

Figure 5 is an elevation of a multiple cleaner unit or device. v i

In the drawings, the letter A designates generally a well formationtester which is of conventional construction and which is connected to aformation perforator or cleaner device B by means of a coupling C orother suitable connecting means. The apparatus, which includes theformation tester A and the cleaner unit or device B, is lowered into awell bore W so as to position the per-forator device B adjacent a wellformation F from which a sample of the formation fluid is to be obtainedfor a formation test. The formation tester A has a usual packing elementor sealing means 19 which is adapted 1 fluid with the formation tester.

to engage in sealing contact with the wall of the well bore W above theformation F. A sample of the. fluid in the formation F is obtained bythe opening of the usual valve (not shown) in the formation tester Aand, as will be explained in detail, the cleaner device B is firedsubstantially simultaneously with the opening of such valve to therebyeifect a cleaning or removal of the mud cake from the wall of the wellbore substantially simultaneously with the taking of the sample of theformation Thus, prior to the formation of any new mud cake or other wallcake on the wall of the well bore adjacent the well formation F, the

flange -21. The upper-end of-the support sleeve 20 is connected byinternal threads 26a or other suitable means to a pipe or tube 22 whichin turn is connected with the coupling'collar or sleeve C (Figure l) Anactuator section/24 is disposed below the upper flange 21 and anexplosive charge section 25 is disposed below the actuator section 2.4.A base flange 26 is threaded by threads 26a or other suitable connectingmeans to -the' support sleeve 20 for retaining the actuator section 24and charge section 25 thereabove. The base flange 26 is locked inposition by an annular locking sub 27 which is threaded or otherwisesuitably connected to the lower end of the support sleeve 2.0 and whichhas a radial flange 27a which abuts against the lower side of the baseflange 26. The sub 27 is connected to a slotted or perforated pipe Swhich serves as a strainer or screen in the known manner during thetaking of the fluid sample with the formation tester. I

The actuator section 24 is in the form of a ringof steel or othersimilar material and is substantially solid inf-projecting into a gnideslot 4 1 whiletheother 'end except for an actuator chamber 3t which isformed therein. The chamber 30 is closed by a removable cover plate 32which is retained in position by asuitable connecting means .such asscrews 33 (Figure 3). vThe removable cover plate 32 has laterallyextending ports 34 and 35 which are in fluid communication with theactuator chamber 30 (Figure 4). v

Within the chamber 30, a cylinder 36 is formed in which a piston 37 ispositioned for relative movement Y therein.

annular seal rings 38 formed'of rubber or other elastic The piston 37has a seal means such as'the material, mounted thereon to maintain theinner portion 36a of the cylinder 36 sealed off from the rest of thecylinder 36 and the actuator chamberfitl, whereby air 'is confinedwithin the closed cylinder portion 36a. A spring 39 or other resilientmeans is mounted within the cylinderfifi'and is confined between thepiston. 37 I and 1 the inner wall 55b of the cylinde1 36. eratur rod 40extends from the piston 37 with one portion thereof projects into asimilar guide slot 42 formed in the cover plate 32, whereby the movementof the piston 1s guided to prevent tilting of the piston 37 in thecylinder 36. The operating rod 40 has a longitudinal cam slot 43 formedtherein through which projects the upper end of a cocking lever 44 whichis pivoted at pivot pin 45. A hammer 46 is mounted at the lower end' ofthe cocking lever'44 and such cocking lever 44 is '1iormally*urged in aclockwise direction (as viewed in Figure 4)bya hammer spring 47. r 'fAbove the operating rod 40 a'latch lever 50 is located which is pivotedat pivot pin 51. The latching lever 50 is urged downwardly bylatchspring 52, but the downward movement of the latching lever 50 is limitedwhen the operating rod 40 is in the unarmed position (Figure 4) byreason of the contact of a cam 53 with the upper surface of theoperating rod 40 (Figure4). At the outer end of the latching lever'50 islatch 54 which is retained in a raised or released position (Figure 4)when the operating rod 40 is in the unarmed position. Upon a movement ofthe operating rod 40 to the left (as viewed in Figure 4) to position therod 40in an armed-position, the cam 53 drops into the opening 43 and thelatch 54 engages the upper end of the cocking lever 44 to thereby putthe actuator device into an armed position for firing (Figure 2). It isbelieved evident that the wall 43a is preferably so positioned withrespect to the cam 53 that it holds the latch lever 50 in the raisedposition (Fig. 4) until the upper end of the cocking lever 44 ispositioned to the left of the latch 54, but even if the wall 43a is sopositioned with respect to the cam 53 so as to permit the cam 53 to dropinto the opening 43 prior to the positioning of the upper end of thelever 44 to the left of the latch 54, the lever 44 can, still be movedinto its latching position to the left of the latch 54 by a cammingaction ofthe lever 44 with the -right inclined surface of the latch54.to raise the lever 50 sufficiently,

for the upper end 'of the lever 44 to pass to the left of the shapedcharge 62 is preferably lined with a plastic (not shown) such as a vinylresin, the fragments of which do not interfere with the operation of theformation tester A. It will be observed that the detonator lead cord 60is positioned at the apex of the acute angle 62a of the explosive charge62. The inner, end 60a of the primacord detonator lead 60 is positionedadjacent the lower end 57a of thedetonator'cord 57am is compressed intocontact therewith by the lower spline or key 63 on the steel ring 25awhich extends into the keyway 59 in the support sleeve 20. Similarlyspline 64 is formed on the ring 25a and also extendsvinto the keyway59', but it is narrow enough so that it does not contact the detonatorthe latch 54, at which time the lever 50 will of course drop by gravityto prevent the return of the lever 44 to the right until. such time asthe fluid pressure inthe chamber 30 is reduced as explained hereinafter.The rod is moved to the left when the fluid pressure in the chamber 30acts on the piston 37 with a force in excess of the strength of thespring 39. As the piston 37 is moved inwardly the air in the closedportion 36a of the cylinder 36 is compressed. It will also be evidentthat upon a movement of piston 37 and the operating rod 40 to the right(as viewed in Figure 4) by reason of a reduction in the fluid pressurein the chamber 30, the inner Wall 43a of the cam slot 43 engages withthe cam 53 V to effect a raising of the latch lever 50, whereby thelatch The percussion primer 56 is connected to a primacord detonator 57which extends from an opening 58 in the actuator ring 24 into a key way59 formed in the external surface of the support sleeve 20. The lowerend 57a of the primacord detonator 57 terminates at the lower end of thekeyway 59 and adjacent the inner end of a prirnacord 60 which extends inan annular ring (Figgures 2 and 3) around the annular explosive 62 forthe purpose of detonating the explosive 62 upon the firing of thepercussion primer 56. The explosive 62 is cast or otherwise formed inthe annular grommet shaped steel collar 25a, such explosive being of thepentolite type or of any other common type customarily used in the jetperforating of oil well casing; Preferably, the exposed face of the castexplosive 62 is formed with an acute angle 620 so as to obtain a shapedcharge blast in the horizontal plane. For mechanical protection, theface of cord 57. Also, the actuator ring 24 has aspline 65 which alsoextends into'the keyway 59. By means of the splines 63, 64 and 65, theactuator ring 24 and the charge ring 25 are both properly aligned witheach other during assembly and are maintained in proper alignment duringuse. I a

In using the apparatus of this invention, the apparatus illustrated inFigure 1 is lowered into the well bore W on the empty drill pipe T andthe formation tester A is positioned in the usual manner so as to placethe packing or sealing element 10 in sealing contact with the wall ofthe well bore at a suitable point above the formation to be tested. Thelength of the'pipe 22 is such that the cleaner device B is positionedadjacent the well formation F which is to be tested.' It should bepointed out that during the lowering of the apparatus of Figure 1 intothe well bore, the device is being lowered through drilling mud or wellfluid which ismaintained under a pressure which is sufiicient to'preventa flow of fiuid from the formation F and any other formation which hasbeen penetrated. The cleaner device B is so constructed for safetypurposes that it is not armed for detonation or firing until theapparatus has been lowered into the drilling mud or well fluid. 'Thus,when the predetermined pressure oftthe'mud or other fluid in the wellbore acts npon'the cleaner or perforator device B, the .device is movedto its armedfor cocked position, that is, the position for firing(Figure 2). During the arming orcocking of the actuator section 24 fromits unarmed position (Figure 4):; the piston 37 is moved to the left bythe well formation F, a valve of conventional construction (not shown)within the formation tester A is opened so as to permit fluid flowthrough the screen S and the bore of the support sleeve 20 and upwardlythrough the inside,

of the pipe 22 to the interior of the formation tester A. When suchvalve in the formation tester A is thus opened, the fluid pressure inthe area adjacent the formation F is reduced due to the flow of. thefluid from the well bore W upwardly into the formation tester A.Substantially simultaneously with the opening of the valve in theformation tester A, the cleaner device B is detonated or fired becausethe reduction in the fluid pressure in the well bore which is caused bythe opening of the valve in the formation tester A also results in areduction in the fluid pressure on the outer surface of the piston 37,whereby the urging force of the spring 39 and the compressed air withinthe portion 36a of the cylinder 36 becomes greater than the fluidpressure externally of the piston 37 to thereby force the piston 37 tothe right (as viewed in Figures 2 and 4). The movement of the pistonaway a from the cylinder wall 36b causes the end Wall 43a of the camslot 43 to slide relative to the cam 53 to thereby force the latch 1ever50 upwardly to its raised position (Figure 4) and thereby releases thelatch 54 from the upper end of the cocking lever 44 whereupon the ham mer spring 47 pivotally swings the cocking lever 44 clockses me wise (asviewed in Figure 4) to cause the hammer 46 to contact the primer 56.Thus, the primer is detonated to detonate the detonator cord 57 which inturn fires or detonates the primacord 60 for exploding the castexplosive 62.

. From the above it will appear that firing means is provided byprimacord 60, detonator cord 57, primer S6, hammer '46, spring 47,cocking lever 44, latch lever 50, and spring 52 which detonates charge62. It will further appear that arming means are provided by piston 37,and the shoulder 66 on rod 40. Of course spring 39 and fluid trapped inthe closed portion 36a of cylinder 36 resist movement of the piston 37when the piston is exposed to an increase in pressure. The spring 39holds piston 37 and rod 40 in a position to engage cam 53 and maintainthe firing mechanism in unarmed position until the device is inserted ina well and subjected to a predetermined well fluid pressure. It willfurther appear from the above that means for actuating the firing meansby releasing the firing means from armed or cocked position to permit itto detonate charge 62 is provided by spring 39 and the pressure trappedin closed portion 36a of cylinder 36 moving rod 40 to a position whereinner wall 43a of cam slot 43 engages cam 53 to lift lever 50 to aposition where latch 54 on lever 50 releases lever 44 upon a reductionof well fluid pressure on piston 37.

Since the cast explosive is shaped with the acute angle 62a, theexplosion occurs in a substantially horizontal plane so that there is nosubstantial thrust or force longitudinally on the apparatus. Theelimination of such longitudinal thrust is important because it preventsthe unsetting or release of the packing element of the formation testerA from the wall of the well bore.

The explosion from the charge 62 effects a cleaning off of the mud cakeor wall cake which is formed on the interior of the well bore adjacentthe well formation F. Since the well fluid in the well bore is at areduced pressure at the time of the detonation of the explosive charge62, it is more effective in such cleaning action. Also, because thefiring of the explosive charge 62 occurs when the valve of the formationtester A is opened, the mud cake or wall cake is removed for the takingof the sample of fluid and new wall cake does not form until after thefluid sample has been obtained. Therefore, it is believed evident thatthe mud cake which normally often interferes with the taking of a testsample from a well formation cannot interfere with the taking of theformation test sample when using the apparatus of this invention. It isof course evident that a relatively small volume of the drilling fluidtrapped below the packer -will be obtained when the formation sample isbeing taken from the well.

In the usual formation tester, a valve is opened to permit the fluidfrom the well to enter the drill stem or drill pipe and the valveremains open long enough to obtain the desired sample. Of course, whenthe valve is first opened, the drilling mud or other fluid in the wellbelow the packer 10 will first enter the drill pipe but the valve of theformation tester is permitted to remain open for a sufiicient length oftime to allow well fluids from the formation to enter in sufficientquantity that the ratio of the drilling mud which has entered is verysmall to the total quantity of liquid finally trapped by the formationtester device. In this manner accurate sampling can be carried out.

In Figure 5, a second cleaner device B is connected to the cleanerdevice B and is substantially identical in construction so that twoformations F and F can be cleaned of wall cake at the same time. Thecylinder 75 which is utilized for connecting together the cleaner unitsB and B can be of various lengths so as to vary the distance between theunit B and B to accommodate use with well formations which are spaceddifierent distances from each other. As will be well understood, thedetonator cord or primacord 57 in the cleaner device B can be lengthenedto contact detonator cords 60 in both the units B and B so that a singleactuator section can fire both units sub stantially simultaneously.Thus, it would be unnecessary to have an actuator section 24 in the unitB but instead it would merely include one or more charge sections 25;

Also, although only one charge section 25 is included in theillustration of the invention in the drawings, it will be evident thatmore than one section 25 could be usedif desired.

' Although the wall'cleaner B of this invention is particularly suitablefor use in combination with the formation tester A as described above,it should also be pointed out that the device B can be used effectivelyas a casing cutter in pulling stuck pipe from a well bore. Other uses ofthe device B will readily occur to those skilled in the art.

The foregoing disclosure and description of the inven-- tion isillustrative and explanatory thereof, and various changes in the size,shape and materials, as well as in the details of the illustratedconstruction, may be made within the scope of the appended claimswithout departing from the spirit of the invention.

What is claimed is:

1. A device for cleaning the wall of a well bore adjacent a wellformation to facilitate the obtaining of a test sample from saidformation, comprising an annular explosive charge adapted to be explodedin the well bore for blasting off a portion of the wall cake coveringthe wall of the well formation, means for supporting said charge fordetonation in the well bore, firing means for detonating said charge,means for arming said firing means, means for actuating the firing meansresponsive to reduction of well fluid pressure to a predetermined valuefor detonating said charge substantially concurrently with the taking ofsaid test sample whereby a portion of the wall cake is removed duringthe taking of the test sample so that the Wall cake does not interferewith the taking of such sample.

2. The structure set forth in claim 1 including means for maintainingthe firing means in unarmed position until the cleaning device issubject to a predetermined well fluid pressure.

3. A device for cleaning the wall of a well bore adjacent a wellformation to facilitate the obtaining of a test sample from saidformation, comprising an annular explosive charge adapted to be explodedin the well bore for blasting off a port-ion of the wall cake coveringthe wall of the well formation, means for supporting said charge fordetonation in the well bore, firing means for detonating said charge,arming means for arming the firing means upon exposing the arming meansto a predetermined increase in fluid pressure by inserting said cleanerdevice into a well bore, and means for releasing the firing means fromarmed position to detonate said charge.

4. A device for cleaning the wall of a well bore adjacent a wellformation to facilitate the obtaining of a test sample from saidformation, comprising an annular explosive charge adapted to be explodedin the well bore for blasting off a portion of the Wall cake coveringthe wall of the well formation, means for supporting said charge fordetonation in the well bore, firing means for detonating said charge,arming means for arming the firing means upon exposing the arming meansto a predetermined increase in fluid pressure by inserting said cleanerdevice into a well bore, and means responsive to reduction of well fluidpressure to a predetermined value for releasing the firing means fromarmed position to detonate said charge.

5. A device for cleaning the wall of a well bore adjacent a Wellformation to facilitate the obtaining of a test sample from saidformation, comprising an annular explosive charge adapted to be explodedin the well bore for blasting off a port-ion of the wall cake coveringthe wall of the well formation, means for supporting said charge fordetonation in the well bore, firing means for '7 detonating said charge,means for maintaining the firing means in unarmed position until thecleaning device is inserted into a well bore, armingmeans for arming thefiring means upon exposing the arming means to a predetermined increasein fluid pressure by inserting said cleaner device into a well bore, andmeans for releasing the firing means from armed position to detonatesaid charge.

6. A device for cleaning the wall of a well bore adjacent a wellformation to facilitate the obtaining of a test sample from saidformation, comprising an annular explosive charge adaptedto be explodedin the well bore for blasting ofi a portion of the wall cake coveringthe wall of the Well formation, means for supporting said charge fordetonation in the well bore, firing means for detonating said charge,means for maintaining the firing means in unarmed position until thecleaning device is inserted into a well bore, arming means" for armingthe firing means upon exposing thelarming means to a prcdeterminedincrease in fluid pressure "by inserting said cleaner device intoa wellbore; and means responsive to' a reduction in bore hole pressure fluidto a predetermined value for releasing the firing means -from armedposition to detonate said charge.

References Cited in the file of this patent

